Answer:
141
Step-by-step explanation:
141
This problem is mainly concerned with setting up an equation.
let's add the interest rates times their respective investment amounts:



simplify:

sum of interest:

1780 = (9000+x) 0.10 + x 0.06 + (11000-2x)0.08


solution:
He does not have any invested in the 6%, while he has 9000 invested at 10% and 11,000 invested at 8%
to check:


So this ended up being a trick problem because he does not actually have any invested in the 6% option.
This is a 45-90-45 triangle so in order to find the answer we have to multiply the hypotenuse, 6, by the square root of 2 or radical 2. Then multiply top and bottom by radical 2. Then simplify.
It will take her 5 5/8 hours to read 3/4 of the book
<h3>Ratio and proportions</h3>
Given that Elisabeth reads 1/5 of her book in 1 1/2 hours, this is expessed as:
0.2 of a book = 1.5 hours
In order to determine the time taken to read 0.75 part of the book, we will have:
0.75 of a book = x
Take the ratios
0.2/0.75 = 1.5/x
0.2x = 1.125
x = 1.125/0.2
x = 5.625
Hence it will take her 5 5/8 hours to read 3/4 of the book
Learn more on ratio and proportion here: brainly.com/question/19994681